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PDBsum entry 1wsd
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References listed in PDB file
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Key reference
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Title
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High-Resolution crystal structure of m-Protease: phylogeny aided analysis of the high-Alkaline adaptation mechanism.
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Authors
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T.Shirai,
A.Suzuki,
T.Yamane,
T.Ashida,
T.Kobayashi,
J.Hitomi,
S.Ito.
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Ref.
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Protein Eng, 1997,
10,
627-634.
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PubMed id
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Abstract
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M-protease is a subtilisin-family serine protease produced by an alkaliphilic
Bacillus sp. strain. Optimal enzymatic activity of the protein occurs at pH
12.3. The crystal structure of M-protease (space group P2(1)2(1)2(1), a = 62.3,
b = 75.5, c = 47.2 A) has been refined to a crystallographic R-factor of 17.2%
at 1.5 A resolution. The alkaline adaptation mechanism of the enzyme was
analyzed. Molecular phylogeny construction was used to determine the amino acid
substitutions that occurred during the high-alkaline adaptation process. This
analysis revealed a decrease in the number of negatively charged amino acids
(aspartic acid and glutamic acid) and lysine residues and an increase in
arginine and neutral hydrophilic amino acids (histidine, asparagine and
glutamine) residues during the course of adaptation. These substitutions
increased the isoelectric point of M-protease. Some of the acquired arginine
residues form hydrogen bonds or ion pairs to combine both N- and C-terminal
regions of M-protease. The substituted residues are localized to a hemisphere of
the globular protein molecule where positional shifts of peptide segments,
relative to those of the less alkaliphilic subtilisin Carlsberg, are observed.
The biased distribution and interactions caused by the substituted residues seem
to be responsible for stabilization of the conformation in a high-alkaline
condition.
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